Disruptive water main breaks happen more often than you think

Blame the old pipes.
water main break caused water to run on to the times square subway lines

A water main break in Times Square shut down subway service. MTA / Flickr

This week, a major water main break in Times Square, New York created waves of disruptions at the city’s busiest subway station. Sheets of water dramatically cascaded down onto subway tracks below—an urban underground waterfall. The culprit was a 127-year-old cast iron pipe that was a few years past its expected lifespan, according to AP

Although the event precipitated a mad scramble to dig, scoop, find and fix the mess, not to mention cleaning and pumping up the aftermath, water main breaks are actually not that uncommon. A 2021 report from the American Society of Civil Engineers estimates that there is a water main break every two minutes in the US. The cost for replacing all the pipes in the country before they reach the end of their life will be over $1 trillion

There were around 400 water main breaks in New York City last year, and the metropolis has been spending more than $1 billion to upgrade its approximately 6,800 miles of aging infrastructure, including water and sewer lines. New York isn’t an anomaly either. Los Angeles has also rolled out a $1.3-billion plan to gradually replace the deteriorating pipes that run beneath the major city. 

So what causes a water main to rupture? A variety of factors. Changes in temperature, water pressure, soil conditions, climate change, a stray tree root, as well as ground movements due to construction, earthquakes, and wear and tear can all play a role. The material that makes up the water mains doesn’t matter as much as the age. Existing water mains can be made of iron, cement, and even wood. 

The number one reason that water main breaks happen so often is the age of the US’s water infrastructure. “Imagine putting anything 120 years old and assuming that it’s going to function the way it did 120 years ago with the demands we put on it now,” Darren Olson, vice chair of the 2021 Report Card for America’s Infrastructure and a water infrastructure expert from Chicago, tells PopSci. “When these water mains were put in 120-plus years ago, nobody envisioned what New York would be and the types of stresses on these systems, especially that we’re facing recently with climate change.”  

[Related: How ‘underground climate change’ affects life on the Earth’s surface]

Extreme weather like droughts or floods can create wild fluctuations in the water levels at treatment plants. The swings in temperature, such as the increasingly crazy freeze-thaw cycles in the colder seasons, can cause pipes to expand and contract more dramatically, making them more susceptible to damage. 

“They estimate that 6 billion gallons of treated water is lost each day in the US. That’s like 9,000 swimming pools of water that we just lose due to leaks or water main breaks,” says Olson. And these breaks can cause a ripple of secondary problems. “A water main break can not only flood something, but imagine the businesses that are relying on that water. It could be a manufacturing plant, it could be a restaurant,” he adds. “An estimated $51 billion of economic loss for water-relevant industries occurs each year because of water main breaks.” 

One pipe going down can affect the whole water distribution system. “If you lose pressure in that water system, that pressure is still critical in a water distribution system because it’s forcing the water not only to go to our faucets, but it’s not allowing things to get into the water system,” Olson explains. “Once you have a water main break, and that pressure no longer exists, you can have boil orders on water because there’s not enough pressure on the system to guarantee that you’re keeping other things out of your water supply.” 

To fix a broken pipe, crews have to locate the leak, excavate the segment, isolate it, reroute the water, do the necessary repairs, put it back in service, then put everything else back in order. Water systems are usually looped, meaning there are a number of pathways for water to flow through. Water valve vaults that are stationed throughout the systems allow engineers to shut off a certain section of the system and still keep the unaffected parts in operation.

Small water main repairs could take a couple of hours. For the large water transmission mains, it could take much longer than that. 

[Related: Our infrastructure can’t handle climate disasters. We need to build differently.]

This whole process sounds like a daunting task, and there are so many at-risk pipes. But city engineers are learning to get smart about prevention. One method is using asset management, which is a way of tracking where all of the underground pipes are located, and considering historical issues with them, along with the size, diameter, and material of the pipes. “When you start to look at all of those in a more comprehensive way, you’re able to plan and use the dollars that we have more effectively to replace the oldest, most critical first. And that can help a city better manage their system,” says Olson. 

However, even with good planning, there are certain limitations. One of those is the funding that goes into this effort. “Back in the 1970s, the federal government was contributing 63 percent to all of the water infrastructure that we had,” Olson notes. “Now that’s down to less than 10 percent. It comes down to either the states or the municipalities, or the counties to help to invest in their own systems and fund that investment.” 

The good news is that the 2022 Bipartisan Infrastructure Bill has recognized the need to improve the country’s water infrastructure. “That bill did target money to that [issue] and it’s a good down payment for what we need,” says Olson. “But the need is so vast that that’s just hopefully the start of future federal investment in our water infrastructure.”